Subject: Re: Reference for typical SNRs is public spaces From: "Richard F. Lyon" <dicklyon@xxxxxxxx> Date: Fri, 24 Jan 2014 22:16:15 -0800 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--001a11c399ea7aa8e904f0c56952 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I think Bill's point, which I agree with, is that the SNR is not determined by the noise in the space as much as it is by people trying to communicate. The SNR that he estimates is not "in the space", but rather "at the ears of the listener" when the talker is trying to communicate to that particular listener, above the noise. Other people trying to communicate to different listeners make noise for this one. The SNR is therefore roughly constant, somewhere near 0 dB, almost anywhere that's not too quiet. For me, it's a little higher, after I make people speak up. Dick On Fri, Jan 24, 2014 at 1:51 PM, Bill Woods <Bill_Woods@xxxxxxxx> wrote: > Dear List, > > Since we=92re assuming Andy is asking about speech-to-noise ratio when > referring to SNR in public spaces, I wondered if the question couldn=92t = be > answered by back-of-the-envelope calculations using some assumptions and > articulation index theory (AI). > > It turned out there was quite a long list of assumptions behind the > calculation (see below), but the resultant simple calculation yielded a S= NR > of 0.5 dB, which is quite in line with the values other posters have > indicated may actually be present. Two other facts became apparent as I d= id > this, however, and further motivate my posting. > > First, the long list of assumptions makes apparent the long list of > influences on the SNR in such a situation. These influences need to be > characterized in any attempt to generalize from SNR measurements in a giv= en > scenario, a fact other posters have alluded to. > > Second, it is important to note that much work has been done recently to > model or empirically characterize these influences on speech > intelligibility, and that, while the models may require more computationa= l > power than found on the back of an envelope, they are no problem to execu= te > on current laptop computers. The implication is that it should not be ver= y > difficult to determine a reasonably-accurate distribution of SNRs over wi= de > variation in the assumed listening scenario without any measurements. > Cheers, > Bill > > Bill Woods, PhD > Principal Research Scientist | Starkey Hearing Research Center > 2150 Shattuck Ave. | Suite 408 | Berkeley, CA 94704-1345 > T: 510-845-4876 x 14 *starkey.com* <http://www.starkey.com/> | > *starkeyresearch.com* <http://www.starkeyresearch.com> | *map*<http://map= s.google.com/maps?q=3D2150+Shattuck+Avenue,+Berkeley,+CA+94704&hl=3Den&ll= =3D37.869941,-122.268219&spn=3D0.028152,0.038066&sll=3D37.86923,-122.273197= &sspn=3D0.056305,0.076132&z=3D15> > | *email* <william_woods@xxxxxxxx> > > The assumptions are: > > 1. Talkers have no hearing loss and no cognitive loss. > 2. The talkers are facing each other and speaking in their =93mother > tongue=94. > 3. We know the percent-correct (%C) targeted by the talkers and it is > less than 100% (it=92s a challenging environment). > 4. We know the nature of the speech in such a conversation, from a > low-context vs. high-context perspective. > 5. The talkers are within their critical distance (i.e., ignore > reverberation of talkers=92 speech). > 6. We know the long-term spectral shape of speech at the eardrums. > 7. We know the long-term spectral shape of noise at the eardrums. > 8. The noise is stationary. > 9. The noise is diffuse. > 10. The diffuse noise in combination with diotic direct-wave target > speech generates the equivalent of an =93internal=94 wideband binaural= SNR > improvement of ~1.0 dB over monaural listening. > 11. Overall level is not too high (i.e., no =93roll-over=94 effect for > intelligibility has occurred). > 12. We=92re not including lip reading. > > > These assumptions allow one to, first, determine the AI needed to achieve > the assumed target %C given the assumed type of speech, and, second, > determine the SNR required with the assumed spectral shapes to obtain tha= t > AI. > > For instance, assuming talkers want 95%C with =93unfamiliar sentences=94 = then > using the polynomial fits from Sherbecoe and Studebaker (JASA 1990) of th= e > ANSI S3.5-1969 transfer functions between AI and %C, our talkers would ne= ed > an AI of 0.45. If we assume the noise and speech have the same long-term > spectral shape then the SNR can be determined from (SNR+12)/30=3D0.45 > (staying with the 1969 AI method), yielding SNR =3D 1.5 dB. Subtracting = the > binaural SNR improvement yields 0.5 dB. > > *From:* AUDITORY - Research in Auditory Perception [ > mailto:AUDITORY@xxxxxxxx <AUDITORY@xxxxxxxx>] *On Behalf Of > *Andy Sabin > *Sent:* Wednesday, January 22, 2014 9:53 AM > > *To:* AUDITORY@xxxxxxxx > *Subject:* Reference for typical SNRs is public spaces > > Hi List, > > Can anyone point me to a reference showing SNRs that are typically > observed in public spaces (e.g., restaurants, bars ...etc)? I can find th= is > info for overall SPL, but am having a hard time finding it for SNR. > > Thanks > Andy Sabin > > --001a11c399ea7aa8e904f0c56952 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div>I think Bill's point, which I agree with, is that= the SNR is not determined by the noise in the space as much as it is by pe= ople trying to communicate.=A0 The SNR that he estimates is not "in th= e space", but rather "at the ears of the listener" when the = talker is trying to communicate to that particular listener, above the nois= e.=A0 Other people trying to communicate to different listeners make noise = for this one.=A0 The SNR is therefore roughly constant, somewhere near 0 dB= , almost anywhere that's not too quiet.<br> <br></div>For me, it's a little higher, after I make people speak up.<b= r><br>Dick<br><br></div><div class=3D"gmail_extra"><br><br><div class=3D"gm= ail_quote">On Fri, Jan 24, 2014 at 1:51 PM, Bill Woods <span dir=3D"ltr">&l= t;<a href=3D"mailto:Bill_Woods@xxxxxxxx" target=3D"_blank">Bill_Woods@xxxxxxxx= arkey.com</a>></span> wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> <div> <font face=3D"Calibri" size=3D"3"><span style=3D"font-size:12pt"> <div>Dear List,</div> <div><font face=3D"Times New Roman">=A0</font></div> <div>Since we=92re assuming Andy is asking about speech-to-noise ratio when= referring to SNR in public spaces, I wondered if the question couldn=92t b= e answered by back-of-the-envelope calculations using some assumptions and = articulation index theory (AI).=A0 </div> <div>=A0</div> <div>It turned out there was quite a long list of assumptions behind the ca= lculation (see below), but the resultant simple calculation yielded a SNR o= f 0.5 dB, which is quite in line with the values other posters have indicat= ed may actually be present. Two other facts became apparent as I did this, however, and further motivate my= posting. </div> <div>=A0</div> <div>First, the long list of assumptions makes apparent the long list of in= fluences on the SNR in such a situation. These influences need to be charac= terized in any attempt to generalize from SNR measurements in a given scena= rio, a fact other posters have alluded to.</div> <div>=A0</div> <div style=3D"margin-bottom:12pt">Second, it is important to note that much= work has been done recently to model or empirically characterize these inf= luences on speech intelligibility, and that, while the models may require m= ore computational power than found on the back of an envelope, they are no problem to execute on current lapto= p computers. The implication is that it should not be very difficult to det= ermine a reasonably-accurate distribution of SNRs over wide variation in th= e assumed listening scenario without any measurements. </div> <div>Cheers,</div> <div>Bill</div> <div><font face=3D"Times New Roman">=A0</font></div> <table style=3D"width:282.75pt;margin-left:5.4pt" width=3D"471"> <colgroup><col style=3D"width:282.75pt" width=3D"471"> </colgroup><tbody><tr> <td><font color=3D"#17365D" face=3D"Arial">Bill Woods, PhD<br> <font color=3D"#595959"><span style=3D"font-size:10pt">Principal Research S= cientist=A0|=A0Starkey Hearing Research Center<br> 2150 Shattuck Ave.=A0|=A0Suite 408=A0|=A0Berkeley,=A0CA=A094704-1345<br> T:=A0<a href=3D"tel:510-845-4876%C2%A0x%C2%A014" value=3D"+15108454876" tar= get=3D"_blank">510-845-4876=A0x=A014</a> </span></font></font></td> </tr> <tr> <td><font face=3D"Times New Roman"><a href=3D"http://www.starkey.com/" targ= et=3D"_blank"><font color=3D"blue" face=3D"Arial"><span style=3D"font-size:= 10pt"><u>starkey.com</u></span></font></a><font color=3D"#0000F6" face=3D"A= rial"><span style=3D"font-size:10pt">=A0</span></font><font color=3D"#59595= 9" face=3D"Arial"><span style=3D"font-size:10pt">|</span></font><font color= =3D"#0000F6" face=3D"Arial"><span style=3D"font-size:10pt">=A0</span></font= ><a href=3D"http://www.starkeyresearch.com" target=3D"_blank"><font color= =3D"blue" face=3D"Arial"><span style=3D"font-size:10pt"><u>starkeyresearch.= com</u></span></font></a><font color=3D"#0000F6" face=3D"Arial"><span style= =3D"font-size:10pt">=A0</span></font><font color=3D"#595959" face=3D"Arial"= ><span style=3D"font-size:10pt">|</span></font><font color=3D"#0000F6" face= =3D"Arial"><span style=3D"font-size:10pt">=A0</span></font><a href=3D"http:= //maps.google.com/maps?q=3D2150+Shattuck+Avenue,+Berkeley,+CA+94704&hl= =3Den&ll=3D37.869941,-122.268219&spn=3D0.028152,0.038066&sll=3D= 37.86923,-122.273197&sspn=3D0.056305,0.076132&z=3D15" target=3D"_bl= ank"><font color=3D"blue" face=3D"Arial"><span style=3D"font-size:10pt"><u>= map</u></span></font></a><font color=3D"#0000F6" face=3D"Arial"><span style= =3D"font-size:10pt">=A0</span></font><font color=3D"#595959" face=3D"Arial"= ><span style=3D"font-size:10pt">|</span></font><font color=3D"#0000F6" face= =3D"Arial"><span style=3D"font-size:10pt">=A0</span></font><a href=3D"mailt= o:william_woods@xxxxxxxx" target=3D"_blank"><font color=3D"blue" face=3D= "Arial"><span style=3D"font-size:10pt"><u>email</u></span></font></a></font= ></td> </tr> <tr> <td><font face=3D"Times New Roman"></font></td> </tr> <tr> <td><font face=3D"Times New Roman"></font></td> </tr> </tbody></table> <div><font face=3D"Times New Roman">=A0</font></div> <div>The assumptions are:</div> <ol style=3D"margin:0;padding-left:36pt"> <li>Talkers have no hearing loss and no cognitive loss.</li><li>The talkers= are facing each other and speaking in their =93mother tongue=94.</li><li>W= e know the percent-correct (%C) targeted by the talkers and it is less than= 100% (it=92s a challenging environment).</li> <li>We know the nature of the speech in such a conversation, from a low-con= text vs. high-context perspective.</li><li>The talkers are within their cri= tical distance (i.e., ignore reverberation of talkers=92 speech).</li><li> We know the long-term spectral shape of speech at the eardrums.</li><li>We = know the long-term spectral shape of noise at the eardrums.</li><li>The noi= se is stationary.</li><li>The noise is diffuse.</li><li>The diffuse noise i= n combination with diotic direct-wave target speech generates the equivalen= t of an =93internal=94 wideband binaural SNR improvement of ~1.0 dB over mo= naural listening.</li> <li>Overall level is not too high (i.e., no =93roll-over=94 effect for inte= lligibility has occurred).</li><li>We=92re not including lip reading.</li><= /ol> <div><font face=3D"Times New Roman">=A0</font></div> <div>These assumptions allow one to, first, determine the AI needed to achi= eve the assumed target %C given the assumed type of speech, and, second, de= termine the SNR required with the assumed spectral shapes to obtain that AI= .</div> <div>=A0</div> <div>For instance, assuming talkers want 95%C with =93unfamiliar sentences= =94 then using the polynomial fits from Sherbecoe and Studebaker (JASA 1990= ) of the ANSI S3.5-1969 transfer functions between AI and %C, our talkers w= ould need an AI of 0.45. If we assume the noise and speech have the same long-term spectral shape then the SNR ca= n be determined from (SNR+12)/30=3D0.45 (staying with the 1969 AI method), = yielding SNR =3D 1.5 dB.=A0 Subtracting the binaural SNR improvement yields= 0.5 dB.=A0 </div> <div><font face=3D"Times New Roman">=A0</font></div> <div><font face=3D"Tahoma"><span style=3D"font-size:10pt"><div class=3D"im"= ><b>From:</b> AUDITORY - Research in Auditory Perception [<a href=3D"mailto= :AUDITORY@xxxxxxxx" target=3D"_blank">mailto:AUDITORY@xxxxxxxx= A</a>] <b>On Behalf Of </b>Andy Sabin<br> </div><b>Sent:</b> Wednesday, January 22, 2014 9:53 AM<div class=3D"im"><br= > <b>To:</b> <a href=3D"mailto:AUDITORY@xxxxxxxx" target=3D"_blank">AU= DITORY@xxxxxxxx</a><br> <b>Subject:</b> Reference for typical SNRs is public spaces</div></span></f= ont></div><div class=3D"im"> <div><font face=3D"Times New Roman">=A0</font></div> <div><font face=3D"Times New Roman">Hi List,=A0</font></div> <div><font face=3D"Times New Roman">=A0</font></div> <div><font face=3D"Times New Roman">Can anyone point me to a reference show= ing SNRs that are typically observed in public spaces (e.g., restaurants, b= ars ...etc)? I can find this info for overall SPL, but am having a hard tim= e finding it for SNR.=A0</font></div> <div><font face=3D"Times New Roman">=A0</font></div> <div><font face=3D"Times New Roman">Thanks</font></div> <div><font face=3D"Times New Roman">Andy Sabin</font></div> <div><font face=3D"Times New Roman">=A0</font></div> </div></span></font> </div> </blockquote></div><br></div> --001a11c399ea7aa8e904f0c56952--